going to be the speed. try going to google and typing in " namesco speedtest"
that will give an idea of the download speed, and if yours is less than 2mb (2000kbs) then it will probably not run the tv too well. if you have old telephone wiring and lots of sockets, it will be worthwhile plugging your computer directly into the test point inside the master socket and seeing what speed you get there, or, ask your neighbours what speed they get, and if its much faster than yours, post a message here and i will instruct you how to do the tests etc.
just a word of warning### if your neighbours speed is much faster than yours, do not call BT or whoever you pay your line rental to before making sure all your internal wiring is good, as BT will charge £130 to come out and £90 per hour if the fault is inside your property.